A typical multiple speed automatically shiftable vehicular transmission includes a housing or case having a plurality of planetary gear sets supported within the case. A plurality of fluid actuated clutches and brakes, operatively associated with various ring gears, sun gears, and planet carriers of the planetary gear sets, operate to establish various speed ratios or power flow paths through the transmission. Often, these clutches and brakes are arranged along longitudinal axes of the transmission with each including an annular cylinder for pressurized fluid and a complementary piston reciprocally movable in each cylinder for applying pressure to friction discs to effect clutching or braking. In order to structurally support fixed or rotating elements of those clutches and brakes located toward the middle of the case, it is customary to employ a structural member known as a center support. Typically, center supports are bolted or otherwise held with respect to the case and provide bearing surfaces for rotating elements. Additionally, an extension housing may be provided to close or seal one end of the transmission case. The extension housing is typically bolted to the case for additional support and to seal the case from fluid leakage.
By integrally casting the center support and the case, the stiffness of the case will tend to increase. However, the draft required from the center support to the rear of the case, for a typical casting operation, increases the diameter of the case. In some instances, this increase in the diameter of the case may make the placement of extension housing bolting bosses about the outside periphery of the case impossible or impractical due to vehicular packaging constraints.